Investigators said two mechanics were working on a car gas tank. The tank started leaking, and ignited when their work light fell and landed on the gasoline.
The bulk of the two-alarm fire was out by 6:30, although firefighters battled thick black smoke in addition to the flames.
The fire was contained to the auto repair shop. The two mechanics escaped without injury.
Two nearby homes were evacuated as a precaution.
No one was injured.